Two-stage hydraulic control valve



June 10, 1952 E. R. WALTHERS TWO-STAGE HYDRAULIC CONTROL VALVE Filed Dec. 30, 1949 Inventor. Earle RWaIbheTs,

b ZJKW y His Attorney.

Patented June 10, 1952 TWO-STAGE HYDRAULIC CONTROL VALVE Earle R Walthers, Schenectady, N. Y., assignor to General Electric Com New York pany, a corporation of Application December 30, 1949, Serial No. 135,993 3 Claims. (01. 137-623) This invention relates to two-stage proportional hydraulic control valves and has for its object theprovision of a simple, reliable proportional hydraulic control valve in which the effect of reaction forces is minimized to reduce the-actuating force required to operate the valve while maintaining stable operating conditions therein.

In general, my inventionconsists of a twostage proportional hydraulic control valve in which the operation of a relatively large main valve thereof is controlled in proportional response to the operation of a relatively small concentrically positioned pilot valve.

For a complete understanding of .my invention, reference should be had to the following specification and the accompanying drawing.

which is a cross-sectional view of a hydraulic control valve illustrative of myinvention.

Referring to the drawing; I have shown there-.

in a proportional hydraulic control valve l illustrative of my invention and comprising a housing 2 having a dump passageway-3 and inlet passageway 4," a pair of working passageways and 6, and a hollow cylindrical interior surface 1. Each of the passageways 4-6 is spaced in the housing 2, as shown in thedrawing. Passageways 3 and 4 provide communication between the exterior and interior of the housing 2, and passageways 5 and 6 extend from the exterior of the housing 2 a predetermined distance in the direction of the interior thereof.

A cylindrically-shapedvalve sleeve 8 having a cylindrical bore or interior 9 is assembledin fixed position within the interior surface! of the housing 2. A cylindricallyshaped-main valve lllhaving a hollow cylindrical interior surface II and opposite ends [2, l3"of reduced dian'leterv is slidably positioned in the interior 9 of the valve sleeve 3. The housing 2 is provided with a pair of opposite closed ends l4, l5 having a pair of aligned apertures l6 and I1 respectively located in the opposite ends l4, |5-as shown in Fig. l, toaccommodate respectively the projecting ends [2, l 3 of the main valve l8. A main body portion l8 of the main valve I0 is made ofshorter length than the length of the housing 2 to form' a pair of pressure chambers l9 and 20,.oneat each end of the main valve l0 between adjacent surfaces of the housing ends I4, and I5, the main valve I 0, and the valve sleeve 8.

Within the cylindrically shaped interior surface II of the main valvelfl, I provide a pilot valve 2| having a relatively small-diameter as compared with "the. diameter of the I main valve Ill. The pilot valve 2i is sli'dably positioned'in the interior surface ll of the main valve I8 and has opposite ends 22, 23 exposed to the exterior of the housing 2.

The pilot valve 2| is operated by any suitable device. For example, I prefer'to use a pair of proportional solenoids 24, 25 having respective armatures 26, 21, and respective-operating coils 28 and 29 and positioned one at either end of therpilot valve 2! to provide engagement of the armature 23 of the solenoid with the'end 22 of the pilot valve 2| and engagement of the armature 21 of the solenoid 25 with the end 23 of the pilot valve 2|. An example of proportional solenoids suitable for operation of the pilot valve 2! is shown in U. S. Patent 2,435,817 of Boynton et al., assigned to the same assignee as this present application. The pilot valve'2l is arranged for slidable movement on the interior surface I l of the main valve H) in accordance with the relative energization of the coils 28; 29of the respecteive solenoids 24, 25.

To provide for the passage of fluid under pressure from the inlet passageway 4 tofa selected one of the working passageways 5 and B, depend;

ent upon the slidable position of the main valve It! in the valve sleeve 8, an annular groove 3!] communicating with the passageway 4 is formed in the outer periphery 3| of the valve sleeve 8. A plurality of apertures 32 communicating with the groove 33 are formed in the valve sleeve 8. A pair of spaced annular grooves 33 and are formed in the outer periphery of the main valve ill on opposite sides ofthe aperture 32 of the valve sleeve 3. A pair of spaced annular grooves 35 and 36 communicating respectively with the working passageways 5 and 6 are formed inthe interior surface 1 of the housing 2. ,A pair of spaced annular grooves 3'! and 38 communicating respectively with the annular grooves 35 and 36 are formedin the exterior periphery of the valve sleeve 8. A plurality of spaced apertures 39 communicating with the annulargroove 37 of the valve sleeve 8 and annular groove 33 of the main valve Ill are formed in the valve sleeve 8. A plurality of spaced apertures 40 communicating with the annular groove 38 of the valvesleeve 8 and the annular groove 34 of the main valve [9 V position of the main valve l0, fluid under pressure is prevented from passing to either of the working passageways and 6. However, when the main valve In is slidably moved to the right, communication is established through the groove 33, associated apertures 39 and associated grooves 31 and 35, to the working passageway 5. Thus, fluid under pressure is passed from the passageway 4 to the passageway 5 When the main valve H) is moved to the right. Conversely, when the main valve I0 is moved to the left from the off position, fluid under pressure is passed from the passageway 4 through the annular groove 34 of the main valve l6 and associated apertures 43 and grooves 38 and 36 aligned with the annular groove 34 to the working passageway 6. Moreover, the amount of displacement to the left or right of the main valve H! from the ofi position is determinative of the area of apertures 32 utilized to pass fluid to the selected passageway 5 or B andtherefore determinesthe flow of fluid through the two-stage control valve i.

To operate the main valve |9 in response to the operation of pilot valve 2| by solenoids 24 and 25 and to control the movement of the main valve l6 proportionally to the movement of the pilot valve 2 I, an annular groove 42 is formed in the land 4|. A plurality of apertures 43 aligned with the annular groove 42 are formed in the main valve l0 to provide communication between the annular groove 42 and the interior of the main valve ID. A pair of spaced annular grooves 44 and 45 are formed in the outer periphery of the pilot valve 2|. A pair of spaced annular grooves 46 and 41 are formed in the interior surface H of the main valve It. A plurality of spaced apertures 48 associated with the annular groove 46 are provided in the main valve l6 to provide communication between the annular groove 44 of the pilot valve 2| and the pressure chamber l9, and a plurality of spaced apertures 49 associated with the annular groove 41 are formed in the main valve Hi to provide communication between annular groove 45 of the pilot valve 2| and the pressure chamber 26. It will be noted that the formation of the annular grooves 44 and 45 in the pilot valve 2| provides a land 5|) aligned with the spaced apertures 43 of the main valve [0 when the pilot valve 2| is in the off position, as shown in Fig. 1.

Considering the structure of the main valve it! and the pilot valve 2| as immediately defined above, it will be noted that for the off position of the pilot valve 2|, as shown in Fig. 1, fluid under pressure in the passageway 4 is prevented from passing to either of the pressure chambers H3 or 20 by the land 50. However, when the pilot valve 2| is moved to the right in response to operation of the solenoid 24, the land 50 is also moved to the right, thereby uncovering the apertures 43 in the main valve H] to permit the passage of fluid under pressure from the passageway 4 through the apertures 43, annular groove 44, annular groove 46, and apertures 48 to the pressure chamber l9. Fluid under pressure thereby admitted to the pressure chamber l9 acts upon an annular surface 5| of the main valve ID to force the main valve to the right and thereby allow fluid under pressure in the passageway 4 to be directed to the working passageway 5.

However, the distance through which the main valve I6 is moved to the right is dependent upon the distance through which the pilot valve 2| is moved to the right. That is, the main valve l0 moves to the right until the aperture 43 thereof is again aligned with the land 50 of the pilot valve 2|, whereupon the land 50 again interrupts the admission of fluid under pressure to the pressure chamber l9 and prevents further movement of the main valve ID to the right. In this manner for each movement of the pilot valve 2| to the right, as governed by the operation of the solenoids 24 and 25, the main valve In follows in response to fluid pressure established in the pressure chamber l9 until the main valve ID has moved the same distance to the right and the aperture 43 of the main valve 10 is aligned with the land 5|] of the pilot valve 2|. Moreover, since the distance through which the main valve I0 is moved to the right determines the area of the apertures 32 uncovered, the rate of fluid flow from the passageway 4 to the passageway 5 is therefore controlled proportionally to the relative energization of the solenoids 24 and 25.

In the same manner, when the pilot valve 2! is moved a predetermined distance to the left, fluid under pressure is passed through-the aperture 43 of the main valve H], the annular groove 45 of the pilot valve 2|, and the annular groove 41 and associated apertures 49 of the main valve in to the pressure chamber 26. Fluid pressure thereby established in the pressure chamber 20 acts upon an annular face 52 of the main valve it to move the main valve ill a corresponding distance to the left, thereby admitting fluid under pressure to the working passageway 6 from the inlet passageway 4 and controlling the flow thereof proportionally to the relative energization of the solenoids 24 and 25. Thus, the movement of the main valve It to pass fluid under pressure from the passageway 4 to a selected one of the passageways 5 and 6 is controlled proportionally to the movement of the pilot valve 2| by the solenoids 24 and 25.

To better understand the remaining operations and structure of the twostage valve I have shown a cross-sectional view of a fluid motor 53 comprising a housing 54 having a cylindrically shaped interior 55, a piston 56 slidably positioned in the interior of the housing 54, and a piston rod 51 rigidly connected to the piston 56 and slidably positioned in an aperture 58 in an end 59 of the motor housing 54. The piston 56 divides the fluid motor 53 into two chambers 60 and 6|.

To operate the fluid motor 53 from the control valve the working passageways 5 and 6 are connected respectively to the chambers 60 and 6| of the fluid motor 53 by a pair of tubes 62 and 63, or by other suitable means. Considering the operation of the valve in connection with the fluid motor 53, it will be noted that when the main valve ID of the control valve is moved to the right, fluid under pressure is passed through the working passageway 5 of the valve to the pressure chamber 50 of the fluid motor 53 forcing the piston 56 thereof to the right providing fluid is not locked in the chamber 6|. To provide for the exhaust of fluid from the chamber 6| to permit movement of the piston 56 to the right, a plurality of spaced apertures 54 and an annular groove 65 are formed in the valve sleeve 8. The apertures 64 and groove 65 provide communication between the dump passageway 3 of the housing 2 and the annular groove 34 of the main valve l0 when the main valve is moved to the right. Thus, when the main valve is moved to the right, communication is established between the chamber 6| of the fluid motor 53 and the dump passageway ace 0,348

3 of the valve I through annular groove 36 of the housing 2, annular groove '38 and apertures 46 of the valve sleeve 8, annular groove 34 of the main valve I6, and apertures 64 and annular groove 65 of the valve sleeve 8.

When the main valve I6 is moved to the left, fluid under pressure is passed from the passageway 4 through the working passageway 6 to the chamber 6| of the fluid motor 53 causing the piston 56 to move to the left providing the fluid is not locked in chamber 66 of the fluid motor 53. To provide for the exhaust of fluid from the chamber 66 when the main valve I6 is moved to the left, a plurality of spaced apertures 66 and an annular groove 61 are provided in the valve sleeve 8, the apertures 66 and annular groove 61 being aligned with the dump passageway 3. Thus, when the main valve I6 is moved to the left, communication is established between the chamber 66 of the fluid motor 53 and the dump passageway 3 through tube 62, passageway 5, annular groove 35 of the housing 2, annular groove 31 and apertures 39 of the valve sleeve 8, annular groove 33 of the main valve l6, and apertures 66 and annular groove 5! of the housing 2.

A consideration of the structure of main valve l as thus far described will indicate that when fluid under pressure is admitted to the pressure chamber I9 of the valve I to move the main valve ID to the right, such movement is .prevented unless fluid stored in the pressure chamber 26 on a previous operation of the main valve I6 to the left is exhausted. Therefore, to exhaust fluid from the pressure chamber 26 of the control valve I on movement of the main valve In to the right, I provide a plurality of spaced apertures 68 and an annular groove 69 positioned in the main valve I6. Communication is thereby provided between the pressure chamber 26 and the dump passageway 3 through the apertures 49 and annular groove 4! of the main valve I6, the annular groove 45 of the pilot valve 2|,

' the apertures 68 and annular groove 69 of the main valve I6, and the apertures 64 and annular groove 65 of the valve sleeve 8 when the main valve |6 is moved to the right.

In addition, a plurality of spaced apertures I6 and an annular groove II are formed in the main valve I6 to exhaust fluid under pressure from the pressure chamber I9 of the control valve I to the dump passageway 3 through the apertures 48 and annular groove 46 of the main valve I6, the annular groove 44 of the pilot valve 2|, the apertures I6 and annular groove II of the main valve I6, and the apertures 66 and annular groove 61 of the valve sleeve 8 when the main valve I6 is moved to the left.

Those skilled in the art will understand that to avoid an unstable condition in the operation of a proportional hydraulic valve, such as control valve the ratio of reactive forces to actuating forces therein must be minimized. For example, I have defined the opposing annular vertical surfaces of the grooves 33 and 34 of the main valve I6 by the numbers I2 and I3. Those skilled in the art will understand that when fluid under pressure is passed frm.the apertures 32 across the surface I2 to the annular groove 33, for example, the flow of fluid across the surface I2 results, in accordance with Bernoullis law, in a smaller pressure on the surface I2 as compared with the fluid pressure on the surface I3. That is, a reactive force resulting from the difference in pressures on the surfaces 12 and I3 and dependent upon the rate of c" flow of fluid through the valve Iis established on the main valve I6. If the reactive force is sufficiently small as compared to the actuating force necessary to move the main valve l6, no-

active force developed in the main valve I6 is dependent upon the area of the annular surfaces 12 and I3 of the grooves 33 and 34. Moreover, the area of surfaces I2 cannot be reduced beyond a predetermined minimum depending upon the capacity of the valve. That is, to lessen the area of surfaces I2 by reducing the depth of the annular grooves 33 and 34 reduces the capacity of the valve I6 and therefore is not desirable if the capacity of the valve I6 is to be maintained. Moreover, to reduce the area of surfaces I2 by reducing the diameter of the valve I6 is impos'- sible where the depth of groove required for a given length of groove to maintain the capacity of the valve is greater than the radius of the valve. 7

Since the reactive force of. the main valve I6 is controlled by the area of the surfaces I2 is not susceptible to further reduction, it is necessary therefore to increase the actuating force to maintain a desired ratio of reactive force to actuating force. The actuating force could be increased by increasing the size of the solenoids 24 and 25 and arranging the solenoids to engage and directly operate the main valve I6.

2| in conjunction with the pressure chambersl9 and 26, suflicient pressure is obtained on they relatively large surfaces 5| and 52 to maintain the desired ratio of reactive to actuating force.

The application of the pilot valve 2| introduces a second reactive force in the valve I. That is, the grooves 44 and 45 of the pilot valve 2| form opposing annular vertical surfaces which I have numbered I4 and I5. Thus, fluid under pressure admitted to groove 44, for example, by moving pilot valve 2| to the right, passes over the surface I4 to produce a smaller pressure thereon than is applied to the surface I5. However, the areas of surfaces I4 and I5 are considerably smaller than the areas of surfaces 12 and I3 because of the relatively small diameter of the pilot valve 2| as compared 'tothe diameter of the main valve l6 and because the crosssectional areas required of grooves 44 and 45 are less than the cross-sectional areas required of grooves 33 and 34. That is, groove ,33 requires a cross-sectional area suflicient to pass a flow of fluid determined by the capacity of the valve whereas the groove 44 requires a crosssectional area sufficient only to pass a relatively small quantity of fluid required to pressurize the small chambers I9 and 26. Therefore, since the area of surface I4 is considerably smaller than the area of surface I2, a relatively smaller reactive force is developed in the pilot valve 2! as compared to the reactive force developed in the main valve l6 and proportionately small actu ating pressure is required of the solenoids 2 4 and 25 to maintain a desired ratio of reactive force to actuating force necessary for stable operation of the pilot valve 2|.

Therefore, in accordance with'my invention, I have provided a 'two-stageproportional hyaccuses dislik tonne; alve hich reactive forces re reduced by the a dition oi p o valve to ermit opera ion o t e cont ol va v by a minimum actuating t me t e eb re cin the cost or the actuating means of the valve while maintaining stable operating conditions therein.

Further, by my invention I have produced a two-stage proportional hydraulic control valve of simple structure and reliable operation in which proportional operation between the pilot valve and main valve therein is obtained directl by locating the pilot valve within the main valve 83d by providing Su table cooperatively arranged apertures and annular grooves as described above in detail whereby the use of additional position indicating devices such as springs, linkages, or electrical piekofis required in conventional twoestage proportional hydraulic valves are 1.1 1 ha ed- While I have shown and described a particular m od ment o my in ent on, i will b o vious to those skilled in the art that various changes and modif es one may be made i t pa n from m invention in. it broa er aspects as I tertor aim h a n d c s o cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A two-stage hydraulic control valve comprising a housing having an inlet passageway, a pair of spaced working passageways, and a hollow cylindrical interior, a cylindrical valve sleeve assembled in fixed position in said housing interior, said valve sleeve having a cylindrical hollow interior, a cylindrical main valve in said valve sleeve having a hollow cylindrical interior and opposite projecting ends of reduced diameter, said main valve having an external diameter slightly less than the interior diameter of said valve sleeve so as to be slidably positioned in said valve sleeve, opposite closed ends for said housing, said ends having aligned apertures to accommodate said projecting ends of said main valve and provide for slidable movement of said main valve in said valve sleeve, said valve sleeve, said housing ends and said main valve having adjacent Surfaces forming a pair of pressure chambers, one at each end of said main valve, a cylindrical pilot valve in said main valve having an external diameter slightly less than the interiordiameter of said main valve so as to be islidably iourrlalled in said main valve, said housing, valve sleeve, and main valve having a plural ty of associated spaced apertures and annular grooves to provide for the passage of fluid from said inlet passageway to a selected one of said working passageways de nden p t p tion of, sold them l e i s id ho said valve sl ve, and. sa d. ho sing ha in a ural o aper ur s a d annu ar grooves spaced to p v e tor the removal of fluid from a selected one of said working passageways dependent upon the position of said main valve in said valve sleeve, said main valve, said pilot valve and said sleeve having a plurality oi apertures and annular roove cooperat vely sp ced to p o i e for h remo l of fluid from a selected one of sai presu e hamb s d endent up e pe a io o said ma n valve. said v l e s ve. Said main valve and said pilot valve having a plurality of cooperatively -spaced apertures and annular rooves to admit fluid under p ss e o a lect d one oi sai pressure chambe s d p d upon the operation of said pilot valve to actuate said main valve in a desired direction, and actuating means external of said housing and engaging said ,ends of said pilot valve to operate the same.

2. A two-stage hydraulic control valve comprising a housing having a hollow cylindrical interior, a spaced inlet passageway, a pair of spaced working passageways, and a dump passageway, each of said passageways communicating with the exterior of said housing, a valve sleeve having a cylindrical periphery engaging the interior of said housing and having a hollow cylindrical interior, a main valve slidably positioned in said valve sleeve, said main valve having an outer periphery engaging the interior surface of said valve sleeve, a hollow cylindrical interior of relatively small diameter as compared to the diameter of its outer periphery, and opposite ends of reduced diameter, opposite closed ends for said housing, said housing ends having aligned apertures to accommodate the ends of said main valve, a cylindrical pilot valve slidably journaled in the interior of said main valve, said housing ends, said valve sleev and said main valve having adjacent surfaces formin two pressure chambers one at each end of said main valve to control the slidable movement thereof in accordance with the relative fluid pressures in said pressure chambers, said valve sleeve, said main valve, and said pilot valve having a plurality of associated spaced apertures and annular grooves to admit fluid under pressure to a selected one of said pressure chambers in response to movement of said pilot valve in a selected direction thereby to control the operation of said main valve in response to a selected operation of said pilot valve, said valve sleeve and said main valve having associated spaced apertures and annular grooves to admit fluid under pressure to a selected one of said working passageways in response to the selected movement of said main valve by said pilot valve, said valve sleeve and said main valve having a plurality of associated spaced apertures and annular grooves to pass fluid from a selected one of said working passageways to said dump passageway in response to a selected operation of said main valve, said main valve, said pilot valve and said valve sleeve having a plurality of associated spaced apertures and annular grooves to allow fluid to be exhausted to said dump passageway from the particular one of said pressure chambers in whose direction said main valve is moving on a particular operation thereof to avoid the development of a back pressure on said main valve preventing operation thereof, and actuating means external of said housing and engaging opposite ends of said pilot valve to operate the same.

3. A two-stage hydraulic control valve comprising a housing having an elongated cylindrical interior, a spaced inlet passageway, a pair of spaced working passageways, and a dump passageway, each of said passageways communicating with the exterior of said housing, a valve sleeve having a cylindrical periphery engaging the interior of said housing and a hollow cylindrical interior, a main valve slidably positioned in said valve sleeve, said main valve having an outer periphery engaging the interior surface of said valve sleeve, a hollow cylindrical interior of relatively small diameter as compared to the diameter of its outer periphery and opposite ends of reduced diameter. opposite closed ends for said housing, said housing ends having aligned apertures to accommodate the ends of said main valve, a cylindrical pilot valve slidably journaled in the interior of said main valve, said housing, valve sleeve, and main valve having a plurality of spaced apertures and a plurality of associated annular grooves cooperatively spaced to provide communication be-- tween said inlet passageway and a selected one of said working passageways dependent upon the position of said main valve in said valve sleeve, said valve sleeve having an additional plurality of apertures and annular grooves cooperatively spaced with respect to said first mentioned apertures and annular grooves to exhaust fluid under pressure from a selected one of said working passageways in response to a selected operation of said main valve, a pair of pressure chambers, one at each end of said valve formed by adjacent surfaces of said valve sleeve, said housing ends and said main valve, 9. pilot valve slidably positioned in said main valve, said pilot valve having a pair of spaced annular grooves forming a centrally disposed land portion, said main valve having an additional plurality of spaced apertures and annular grooves cooperatively arranged with respect to said land portion and said spaced annular grooves of said pilot valve to admit fluid under pressure from said inlet passageway to a selected one of said pressure chambers to selectively operactuating means external of said housing and engaging said ends of said pilot valve to operate the same.

EARLE R. WALTHERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,526,709 Tait Oct. 24, 1950 FOREIGN PATENTS Number Country Date 36,009 Sweden Dec. 31, 1913 

